Method and apparatus pertaining to use of multiple sessions with RFID tags

ABSTRACT

At a facility having a first area and a second area that is at least substantially non-overlapping with the first area, these teachings provide for using at least a first RFID-tag reader to read RFID tags in a first inventory state in the first area using a first session protocol while also contemporaneously using a second session protocol to cause the RFID-tag reader to cause RFID tags in the first area to switch to that first inventory state. In a similar manner these teachings also provide for using a second RFID-tag reader to read RFID tags in the first inventory state in the second area using the second session protocol while also contemporaneously using the first session protocol to cause RFID tags in the second area to switch to the first inventory state.

TECHNICAL FIELD

This invention relates generally to radio-frequency identification(RFID)-tag reader systems.

BACKGROUND

RFID tags are known in the art. These so-called tags often assume theform factor of a label or a literal “tag” but are also sometimesintegrated with a host article and/or its packaging. RFID tags typicallycomprise an integrated circuit and one or more antennas. The integratedcircuit typically carries out a variety of functions includingmodulating and demodulating radio frequency signals, data storage, anddata processing. Some integrated circuits are active or self-powered (inwhole or in part) while others are passive, being completely dependentupon an external power source (such as an RFID tag reader) to supporttheir occasional functionality.

There are proposals to utilize RFID tags to individually identifyindividual items. The Electronic Product Code (EPC) as managed byEPCGlobal, Inc. represents one such effort in these regards. EPC-basedRFID tags each have a unique serial number to thereby uniquely identifyeach tag and, by association, each item correlated on a one-for-onebasis with such tags. (The corresponding document entitled EPCRadio-Frequency Identity Protocols Class-1 Generation-2 UHF RFIDProtocol for Communications at 860 MHz-960 MHz Version 1.0.9 is herebyfully incorporated herein by this reference.)

Each EPC-compliant tag has two states: “A” and “B.” The “A” statecomprises the default state and hence represents the tag's state wheninitially powering up. Once a tag has been read its state changes from“A” to “B.” During the “A” state a tag will respond to any reader thatoffers a session query. During the “B” state the tag will not againrespond to a reader using the same session query.

The EPC approach also supports four session protocols that differ withrespect to how a read tag persists a “B” state. In Session “0” a readtag will persist this “B” state until power is lost and then the tagreverts immediately to the “A” state. In Session “1” a read tag willpersist its “B” state for a period of time ranging from 500 ms to 5seconds and will then automatically revert to the “A” state. In Session“2” and “3” a read tag will remain in the “B” state until power is lost.Then, once power is lost, the read tag will persist its “B” state for atleast an additional 2 seconds (the actual persistence duration is leftto the manufacturer and can reach minutes in some cases). In many casesa system designer will choose a particular EPC session protocol andemploy that session protocol throughout a given facility.

In some cases a system designer will seek to provide more-or-lessubiquitous coverage through a given facility (such as a retail store)and thereby have the theoretical ability to read an RFID tag regardlessof where that tag might be located within the facility. There arenumerous (and significant) challenges, unfortunately, to designing anddeploying such a system. On the one hand, continuously prompting allRFID tags to constantly (or even frequently) assume an A inventory statewill typically result in those RFID tags constantly being read. When thefacility includes a large number of RFID tags such a situation canresult in an overwhelming number of reads that can literally prevent thesystem from providing useful data to the system user. On the other hand,leaving read RFID tags in the B inventory state regardless ofcircumstance can leave the system blind to important in-facility eventsas pertain to those RFID tags.

BRIEF DESCRIPTION OF THE DRAWINGS

The above needs are at least partially met through provision of themethod and apparatus pertaining to use of multiple sessions with RFIDtags described in the following detailed description, particularly whenstudied in conjunction with the drawings, wherein:

FIG. 1 comprises a flow diagram as configured in accordance with variousembodiments of the invention;

FIG. 2 comprises a block diagram as configured in accordance withvarious embodiments of the invention;

FIG. 3 comprises a timing diagram as configured in accordance withvarious embodiments of the invention;

FIG. 4 comprises a timing diagram as configured in accordance withvarious embodiments of the invention; and

FIG. 5 comprises a schematic representation as configured in accordancewith various embodiments of the invention.

Elements in the figures are illustrated for simplicity and clarity andhave not necessarily been drawn to scale. For example, the dimensionsand/or relative positioning of some of the elements in the figures maybe exaggerated relative to other elements to help to improveunderstanding of various embodiments of the present invention. Also,common but well-understood elements that are useful or necessary in acommercially feasible embodiment are often not depicted in order tofacilitate a less obstructed view of these various embodiments of thepresent invention. Certain actions and/or steps may be described ordepicted in a particular order of occurrence while those skilled in theart will understand that such specificity with respect to sequence isnot actually required. The terms and expressions used herein have theordinary technical meaning as is accorded to such terms and expressionsby persons skilled in the technical field as set forth above exceptwhere different specific meanings have otherwise been set forth herein.

DETAILED DESCRIPTION

Generally speaking, these various embodiments set forth approaches tointeracting with RFID tags at a facility having a first area and asecond area that is at least substantially non-overlapping with thefirst area. These teachings provide for using at least a first RFID-tagreader to read RFID tags in a first inventory state in the first areausing a first session protocol while also contemporaneously using asecond session protocol to cause the RFID-tag reader to cause RFID tagsin the first area to switch to that first inventory state. In a similarmanner these teachings also provide for using a second RFID-tag readerto read RFID tags in the first inventory state in the second area usingthe second session protocol while also contemporaneously using the firstsession protocol to cause RFID tags in the second area to switch to thefirst inventory state.

By way of an illustrative example the aforementioned first area cancomprise a non-public inventory-storage area of a retail establishmentand the second area can comprise a public sales area where retailcommodities are displayed and made available for purchase. By oneapproach the present teachings can be employed to generally use a firstsession protocol when reading RFID tags in the inventory-storage areaand a second, different session protocol when reading RFID tags in thepublic sales area. Such an approach can serve, for example, to read RFIDtags upon first entering one of these areas.

Furthermore, by one approach the present teachings will help to ensurethat RFID tags remain in a readable state so that such RFID tags areactually read upon so entering such an area. For example, in addition topermitting RFID tags in, for example, the inventory-storage area to beread these teachings will also serve to maintain such RFID tags in aninventory state for the session protocol employed in the public salesarea that will tend to help ensure that such RFID tags are read uponmoving from the inventory-storage area to the public sales area.

These and other benefits may become clearer upon making a thoroughreview and study of the following detailed description. Referring now tothe drawings, and in particular to FIG. 1, an illustrative process 100that is compatible with many of these teachings will now be presented.For the sake of an illustrative example, but without intending tosuggest any specific limitations in these regards, it will be presumedin this description that this process 100 is carried out at a facilityhaving a first area and a second area that is at least substantiallynon-overlapping with the first area. Referring momentarily to FIG. 2, itwill be similarly presumed that this facility 200 includes a controlcircuit 201 (that may, or may not, operably couple to an optional memory202 as desired) that operably couples to one or more first RFID-tagreaders 203 and also to one or more second RFID-tag readers 204.

Such a control circuit 201 can comprise a fixed-purpose hard-wiredplatform or can comprise a partially or wholly programmable platform.These architectural options are well known and understood in the art andrequire no further description here. This control circuit 201 isconfigured (for example, by using corresponding programming as will bewell understood by those skilled in the art) to carry out one or more ofthe steps, actions, and/or functions described herein.

The memory 202 may be integral to the control circuit 201 or can bephysically discrete (in whole or in part) from the control circuit 201as desired. This memory 202 can also be local with respect to thecontrol circuit 201 (where, for example, both share a common circuitboard, chassis, power supply, and/or housing) or can be partially orwholly remote with respect to the control circuit 201 (where, forexample, the memory 202 is physically located in another facility,metropolitan area, or even country as compared to the control circuit201).

This memory 202 can serve, for example, to non-transitorily store thecomputer instructions that, when executed by the control circuit 201,cause the control circuit 201 to behave as described herein. (As usedherein, this reference to “non-transitorily” will be understood to referto a non-ephemeral state for the stored contents (and hence excludeswhen the stored contents merely constitute signals or waves) rather thanvolatility of the storage media itself and hence includes bothnon-volatile memory (such as read-only memory (ROM) as well as volatilememory (such as an erasable programmable read-only memory (EPROM).)

By one approach, one or more of the aforementioned RFID-tag readers 203and 204 may comprise overhead RFID-tag readers that hang suspended fromthe ceiling of the facility 200. Examples in such regards can be found,for example, in U.S. patent application Ser. No. 12/900,191, entitledMETHOD AND APPARATUS PERTAINING TO RFID TAG READER ANTENNA ARRAY, thecontents of which are fully incorporated herein by this reference.

It is presumed for the sake of an illustrative example that theaforementioned first RFID-tag reader(s) 203 is physically disposedwithin the aforementioned first area and the second RFID-tag reader(s)204 is physically disposed within the aforementioned second area inorder for the primary (or exclusive) reading coverage area of eachreader to be similarly contained. Accordingly, the primary readingcoverage zone for the first RFID-tag reader(s) 203 is within the firstarea while the primary reading coverage zone for the second RFID-tagreader(s) 204 is within the second area. That said, in a typicalapplication setting it will not be unusual or unexpected for thecoverage zone of one of the first RFID-tag readers 203 to partiallyoverlap, at least from time to time, with the second area and/or for thecoverage zone of one of the second RFID-tag readers 204 to partiallyoverlap with the first area.

Referring now to FIGS. 1, 2, and 3, at 101 the process 100 provides forusing the aforementioned one or more first RFID-tag readers 203 to readRFID tags in a first inventory state (such as, for example, the EPC “A”inventory state) in the first area using a first session protocol 301(such as, for example, the EPC's session “1”). Contemporaneously, one ormore of these first RFID-tag readers 203 also uses a second sessionprotocol 302 (such as, for example, the EPC's session “2”) to cause RFIDtags in the first area to switch to the aforementioned first inventorystate. (As used herein this reference to a “second” session protocolwill be understood to refer to a session protocol that is different fromthe aforementioned first session protocol.) Those skilled in the artwill understand that the EPC standard includes such a capability.

As used herein, the word “contemporaneously” will be understood toinclude activities/events that are wholly or partially coincident intime, activities/events that are temporally concatenated (immediately orat least close in time—say, within a few seconds), and activities/eventsthat are neither juxtaposed in time or even merely offset in time fromone another but that are separated in time by other activities/eventsthat do not represent a majority of the RFID-tag reader's operationsover some significant period of time such as, for example, one or twohours. Accordingly, while FIG. 3 presents the two session protocols 301and 302 as being temporally concatenated, it will be understood thatthese teachings are intended to have broader applicability in theseregards.

Referring now to FIGS. 1, 2, and 4, at 102 the process 100 provides forusing the aforementioned one or more second RFID-tag readers 204 to readRFID tags in a first inventory state (such as, for example, the EPC “A”inventory state) in the second area using the second session protocol302. Contemporaneously, one or more of these second RFID-tag readers 204also uses the first session protocol 301 to cause RFID tags in thesecond area to switch to the aforementioned first inventory state.

So configured, the RFID-tag readers for a first area of a given facilityare configured to read RFID tags using a first session protocol whilethe RFID-tag readers for a second, different area of that facility areconfigured to read RFID tags using a second, different session protocol.In addition, those RFID-tag readers also, from time to time, cause theRFID tags within their coverage area to switch their inventory states(if a switch is necessary) to the “A” inventory state for the sessionprotocol that corresponds to the RFID-tag readers for other than theircoverage area.

The periodicity by which such RFID-tag readers instruct RFID tags toswitch to the “A” inventory state can vary as desired. By one approachthe periodicity can be regular and even predictable. By another approachthe periodicity can be irregular and even unscheduled at least to someextent. In many application settings it may be useful and sufficient toonly provide that switching instruction at least once (and/or no moreoften than) every one second, two seconds, five seconds, or even tenseconds (with even longer durations being possibly appropriate in someapplication settings).

FIG. 5 presents a more specific working example in these regards. Itwill again be understood that the specifics of this example are notintended to be exhaustive in these regards and are certainly notintended to suggest any particular limitations by way of suchspecificity.

In this example the facility 200 comprises a retail establishment havinga first area 501 that comprises a non-public backroom storage area and asecond area 502 that comprises a public sales floor where variouscommodities are displayed and available for purchase by members of thepublic. A wall 503 serves, at least in part, to separate these two areas501 and 502 with at least one door 504 serving to provide a pathway fromone area to the other by authorized associates. Such arrangements arevery well known in the art and require no further explanation here asidefrom noting that the wall 503 and/or door 504 may, or may not, becomprised (in whole or in part) of materials that block or at leastattenuate radio-frequency carriers.

The aforementioned first RFID-tag readers 203 are situated to at leastprimarily (and possibly even exclusively) provide RFID-tag readercoverage in the first area 501. In turn, the aforementioned secondRFID-tag readers 204 are situated to at least primarily (and possiblyeven exclusively) provide RFID-tag reader coverage in the second area502. Those first RFID-tag readers 203 are transmitting/reading using thefirst RFID-tag reader scheme 300 described above with respect to FIG. 3while the second RFID-tag readers 204 are transmitting/reading using thesecond RFID-tag reader scheme 400 described above with respect to FIG.4.

In the first area 501:

A first RFID tag 505 has a “B” inventory state with respect to the firstsession protocol and an “A” inventory state with respect to the secondsession protocol. Accordingly, this RFID tag 505 will remain quiescentand take no particular action with respect to the transmissions of thefirst RFID-tag readers 203. This is because its “B” inventory statepermits the RFID tag 505 to remain quiescent in response to readinquiries per the first session protocol and its “A” inventory statewith respect to the second session protocol does not require answitching per the occasional instructions from the first RFID-tagreaders 203.

A second RFID tag 506 has an “A” inventory state with respect to boththe first session protocol and the second session protocol. In thiscase, the RFID tag 506 will respond to a read inquiry from the firstRFID-tag readers 203 per the first session protocol in which case theinventory state for the first session protocol will switch from the “A”inventory state to the “B” inventory state. This RFID tag 506 will nototherwise respond to the switching instructions from the first RFID-tagreaders 203, however, because its inventory state for the second sessionprotocol is already the “A” inventory state.

And a third RFID tag 507 has a “B” inventory state with respect to boththe first and second session protocols. In this case the RFID tag 507will not be read by the first RFID-tag readers 203 per the first sessionprotocol due to that “B” inventory state. This RFID tag 507 will,however, switch from the “B” inventory state for the second sessionprotocol to the “A” inventory state for the second session protocol perthe above description.

RFID tag behavior in the second area 502 more or less mirrors theabove-described behavior. In particular, in the second area:

A first RFID tag 508 has an “A” inventory state with respect to thefirst session protocol and a “B” inventory state with respect to thesecond session protocol. Accordingly, this RFID tag 508 will remainquiescent and take no particular action with respect to thetransmissions of the second RFID-tag readers 204. This is because itssecond session protocol “B” inventory state permits the RFID tag 508 toremain quiescent in response to read inquiries per the second sessionprotocol and its “A” inventory state with respect to the first sessionprotocol does not require any switching per the occasional instructionsfrom the second RFID-tag readers 204 as described above.

A second RFID tag 509 has an “A” inventory state with respect to boththe first session protocol and the second session protocol. In thiscase, the RFID tag 509 will respond to a read inquiry from the secondRFID-tag readers 204 per the second session protocol in which case theinventory state for the second session protocol will switch from the “A”inventory state to the “B” inventory state. This RFID tag 509 will nototherwise respond to the switching instructions from the second RFID-tagreaders 204, however, because its inventory state for the first sessionprotocol is already the “A” inventory state.

And a third RFID tag 510 has a “B” inventory state with respect to boththe first and second session protocols. In this case the RFID tag 510will not be read by the second RFID-tag readers 204 per the secondsession protocol due to that “B” inventory state. This RFID tag 510will, however, switch from the “B” inventory state for the first sessionprotocol to the “A” inventory state for the first session protocol perthe above description.

Accordingly, it will be appreciated that RFID tags that move from onearea to the other will be read upon entering the coverage area of therespective RFID-tag reader(s) for the entered area. So, for example,when an associate brings an item having a correspond RFID tag from theback room to the main sales floor the readers for the main sales floorwill likely be able to quickly note the introduction of that RFIDtag/item to the main sales floor. Similarly, if and when an associateremoves an item/tag from the main sales floor and returns the item/tagto the back room, the readers for the back room will likely be able toquickly note this transition. The foregoing benefits accrue, at least inpart, due to the ability of the described approach to maintain RFID tagsin a state such that the RFID tags are each primed and ready to respondto the RFID-tag readers of a different area by being read.

In a real-world application setting it is also possible for the coverageareas of these different RFID-tag readers for different areas partiallyoverlap, either on a continuous basis or from time to time. For example,when opening the door 504 it is possible that some first area RFID tagsmight be read by second area RFID-tag readers because the transmissionsof the second RFID-tag readers 204 might be momentarily sufficient toaccomplish that result. When such a thing happens, of course, the readRFID tag will switch its inventory state from “A” to “B” for thecorresponding session protocol. As a result, without further attention,that already-read RFID tag will not be read when as associate actuallydoes move that RFID tag from the first area 501 to the second area 502.

The above-described teachings, however, will permit the first RFID-tagreaders 203 for the first area 501 to automatically reset such an RFIDtag to the “A” inventory state for the session protocol that serves thesecond area 502. Accordingly, the system will be able to detect whenthat RFID tag does eventually move from the first area 501 to the secondarea 502 because the inventory state for that RFID tag will have beenswitched back to the “A” inventory state for the second sessionprotocol.

So configured, these teachings can serve well in conjunction with anoverall strategy of maintaining most RFID tags in a given facility in aquiescent state for most of the time and generally seeking to prompt aread response only (to whatever extent that can be possible) asimportant events occur (such as moving from one area of a facilityhaving a first purpose (such as storage) to another area of thatfacility have a second, different purpose (such as display and sales)).

These teachings are highly flexible in practice and will accommodate agreat variety of alterations and embellishments. Various sessionprotocols per the EPC standard can be employed for example, as can othersession protocols for other approaches to reading RFID tags. As anotherexample, these teachings will readily accommodate essentially reversingthe above-described handling of inventory states (as the EPC standardallows for reading tags in the B inventory state and then causing theread tag to transition to the A inventory state) if desired. And as yetanother example in these regards, when one of the aforementioned areashas more than one RFID-tag reader, these teachings do not require thateach and every RFID-tag reader in a given such area behave as describedherein. Instead, if desired, only those RFID-tag readers that arelocated near a portal that connects the area in question to a differentarea might be so configured.

These teachings are also readily scaled to accommodate, for example,three or more circumscribed areas that each have a corresponding unique(within the facility) session protocol if desired. Accordingly, and byway of an illustrative example, a first area could comprise a loadingdock receiving area, a second area could comprise a backroom storagearea, a third area could comprise a retail showroom, and a fourth areacould comprise a garden supplies area.

Those skilled in the art will recognize that a wide variety ofmodifications, alterations, and combinations can be made with respect tothe above described embodiments without departing from the scope of theinvention, and that such modifications, alterations, and combinationsare to be viewed as being within the ambit of the inventive concept.

I claim:
 1. A method of interacting with radio-frequency identification(RFID) tags at a facility having a first area and a second area that isat least substantially non-overlapping with the first area, the methodcomprising: using at least a first RFID-tag reader configured to readRFID tags in a first inventory state in the first area using a firstsession protocol while also contemporaneously using a second sessionprotocol to cause the RFID tags in the first area to switch to the firstinventory state with respect to the second session protocol; using atleast a second RFID-tag reader configured to read RFID tags in the firstinventory state in the second area using the second session protocolwhile also contemporaneously using the first session protocol to causethe RFID tags in the second area to switch to the first inventory statewith respect to the first session protocol.
 2. The method of claim 1wherein the first area comprises a public area of the facility and thesecond area comprises a non-public area of the facility.
 3. The methodof claim 2 wherein the facility comprises a retail-sales facility. 4.The method of claim 1 wherein the first session protocol comprisessession 2 as specified by a standard denoted as EPC Radio-FrequencyIdentity Protocols Class-1 Generation-2 UHF RFID Protocol forCommunications at 860 MHz-960 MHz Version 1.0.9 (standard) and thesecond session protocol comprises session 3 as specified by thestandard.
 5. The method of claim 4 wherein the first inventory statecomprises inventory state A and a second inventory state comprisesinventory state B, both as specified by the standard.
 6. A method ofinteracting with radio-frequency identification (RFID) tags at afacility having a first area and a second area that is at leastsubstantially non-overlapping with the first area, the methodcomprising: using a first plurality of RFID-tag readers that are eachconfigured to read RFID tags in a first inventory state in the firstarea using a first session protocol while also contemporaneously using asecond session protocol to cause the RFID tags in the first area toswitch to the first inventory state with respect to the second sessionprotocol; using a second plurality of RFID-tag readers that are eachconfigured to read RFID tags in the first inventory state in the secondarea using the second session protocol while also contemporaneouslyusing the first session protocol to cause the RFID tags in the secondarea to switch to the first inventory state with respect to the firstsession protocol.
 7. The method of claim 6 wherein the first areacomprises a public area of the facility and the second area comprises anon-public area of the facility.
 8. The method of claim 7 wherein thefacility comprises a retail-sales facility.
 9. The method of claim 6wherein the first session protocol comprises session 2 as specified by astandard denoted as EPC Radio-Frequency Identity Protocols Class-1Generation-2 UHF RFID Protocol for Communications at 860 MHz-960 MHzVersion 1.0.9 (standard) and the second session protocol comprisessession 3 as specified by the standard.
 10. The method of claim 9wherein the first inventory state comprises inventory state A and asecond inventory state comprises inventory state B, both as specified bythe standard.
 11. An apparatus comprising: a facility having a firstarea and a second area that is at least substantially non-overlappingwith the first area; at least a first RFID-tag reader configured to readRFID tags in a first inventory state in the first area using a firstsession protocol and that is also configured to contemporaneously use asecond session protocol to cause the RFID tags in the first area toswitch to the first inventory state with respect to the second sessionprotocol; at least a second RFID-tag reader configured to read RFID tagsin the first inventory state in the second area using the second sessionprotocol and that is also configured to contemporaneously use the firstsession protocol to cause the RFID tags in the second area to switch tothe first inventory state with respect to the first session protocol.12. The apparatus of claim 11 wherein the first area comprises a publicarea of the facility and the second area comprises a non-public area ofthe facility.
 13. The apparatus of claim 12 wherein the facilitycomprises a retail-sales facility.
 14. The apparatus of claim 11 whereinthe first session protocol comprises session 2 as specified by astandard denoted as EPC Radio-Frequency Identity Protocols Class-1Generation-2 UHF RFID Protocol for Communications at 860 MHz-960 MHzVersion 1.0.9 (standard) and the second session protocol comprisessession 3 as specified by the standard.
 15. The apparatus of claim 14wherein the first inventory state comprises inventory state A and asecond inventory state comprises inventory state B, both as specified bythe standard.